Answer:
-

Explanation:
Using the rules of exponents
⇔

=

Consider the right side

=

=

=

Now we have
9 =
, that is
3² =

Since the bases on both sides are equal, equate the exponents
- 3a - 9 = 2 ( add 9 to both sides )
- 3a = 11 ( divide both sides by - 3 )
a = -
